I tested both hooked up and unhooked on same day, same conditions and logged the runs. I saw no RPM change either way. What I do know is with the hose hooked up factory style, is the mist and vapor coats the whole intake for sure.
I prefer to run with the blowby running out under the running board rather than coating the intake. After I ran that test that day, I did take out the intercooler to see how much oil I had in there and there was of course the coating and a bit of oil in the bottom of the cooler and intake tubes were coated.
Powerwise, I doubt you'd see a horse or two either way. I did the ROV elimination mod to get rid of the ROV and prevent the oil tank seal from blowing which is has done a good job of. Not coating the intake has just been a bonus.
In the 1400 or so miles I've done this season, I have used zero oil and it is still right at the top of the line on oil tank with ROV mod dumping vapor under the running board.